4 Information requirements

This clause specifies the information requirements for the Geometric validation property representation application module. The information requirements are specified as the Application Reference Model (ARM) of this application module.

NOTE 1  A graphical representation of the information requirements is given in Annex C.

NOTE 2  The mapping specification is specified in 5.1. It shows how the information requirements are met by using common resources and constructs defined or imported in the MIM schema of this application module.

The following EXPRESS specification begins the Geometric_validation_property_representation_arm schema and identifies the necessary external references.

4.1 Required AM ARMs

The following EXPRESS interface statements specify the elements imported from the ARMs of other application modules.

EXPRESS specification:

*)
USE FROM Elemental_geometric_shape_arm;    --  ISO/TS 10303-1004



USE FROM Foundation_representation_arm;    --  ISO/TS 10303-1006



USE FROM Measure_representation_arm;    --  ISO/TS 10303-1118
(*



NOTE 1   The schemas referenced above are specified in the following part of ISO 10303:

Elemental_geometric_shape_arm	ISO/TS 10303-1004
Foundation_representation_arm	ISO/TS 10303-1006
Measure_representation_arm	ISO/TS 10303-1118

NOTE 2   See Annex C, Figures C.1and C.2 for a graphical representation of this schema.

4.2 ARM type definition

This subclause specifies the ARM type for this application module. The ARM type and definition is specified below.

4.2.1 point_or_measure   

The point_or_measure type allows for the designation of the data types Cartesian_point and Measure_item.

EXPRESS specification:

*)
TYPE point_or_measure = SELECT
   (Cartesian_point,
    Measure_item);
END_TYPE;
(*

4.3 ARM entity definition

This subclause specifies the ARM entity for this module. The ARM entity is an atomic element that embodies a unique application concept and contains attributes specifying the data elements of the entity. The ARM entity and definition is specified below.

4.3.1 Geometric_validation_property   

The following properties are allowed:

• centroid: centre of volume of a geometric solid model. In that case, the property_representation shall contain a Cartesian_point. This instance of Cartesian_point shall have the name 'centre point' ;
• volume: amount of space occupied by the solid model. In that case, the property_representation shall contain a Measure_item representing a volume measure. This instance of Measure_item shall have the name 'volume measure';
• surface area: area measurement of the surface of the entire solid or surface model. In that case, the property_representation shall contain a Measure_item representing an area measure. This instance of Measure_item shall have the name 'surface area measure'.

NOTE    The following process may be used to validate an exchange of geometric model.

• The sender populates the geometric validation properties in the exchange file, usually calculated by their CAD systems;
• The receiver performs geometric translations or transformations that are necessary on the solid or surface model;
• The receiver then calculates the properties of the resultant geometry;
• The receiver compares these with the values in the exchange file;
• If they are within an agreed tolerance then the exchange is deemed to have been validated.

EXPRESS specification:

*)
ENTITY Geometric_validation_property;
  property_representation : Representation;
  property_value : point_or_measure;
  validated_model : Geometric_model;
WHERE
  WR1: 'GEOMETRIC_VALIDATION_PROPERTY_REPRESENTATION_ARM.NUMERICAL_REPRESENTATION_CONTEXT' IN TYPEOF(property_representation\Representation.context_of_items) ;
  WR2: property_representation.name IN ['centroid', 'volume', 'surface area'];
  WR3: property_value in property_representation\Representation.items;
END_ENTITY;
(*

Attribute definitions:

property_representation: the Representation that provides the valued characteristics.

property_value: the Cartesian_point in case of the centroid property or the Measure_item in case of the surface area and volume properties, that provides the value of the property.

validated_model: the Geometric_model from which the geometric validation property has been computed.

Formal propositions:

WR1: the context of the property_representation shall be a numerical context. In case of the centroid property, the context shall be a Geometric_coordinate_space.

WR2: the name of the property_representation shall be either 'centroid, 'surface area' or 'volume'.

WR3: the property_value item shall be a member of the items of the property_representation.

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